This invention relates to a completely automatic unit for preparing espresso coffee, in which the various mutually moving parts are operated by the pressurized water delivered by the service pump, further electrical or pneumatic controls being absent.
The known art provides automatic espresso coffee dispensing units comprising mutually moving parts driven by electrical actuators controlled by sophisticated means, to ensure that the coffee powder is subjected to the correct pressure necessary to obtain a drink having the required quality.
Dispensing units of known type are complicated and costly, are difficult and onerous to maintain, and have to be installed by specialised personnel possessing the necessary equipment.
The main object of the invention is to provide an espresso coffee dispensing unit of simple and economical construction, installation and assembly, and which can be used without difference either in automatic machines for professional use, or in machines intended for domestic use.
A further object of the invention is to provide a coffee dispensing unit of the aforesaid characteristics, which can be used with loose ground coffee, or with sachets or capsules pre-filled with ground coffee.
A particular object of the invention is to provide a dispensing unit able to use those pre-filled sachets of coffee powder of the capsule type comprising a semi-rigid cup with a filtering base and top, and provided with a support collar.
The main object of the invention is attained by an automatic espresso coffee dispensing unit comprising hot water delivery means and, for containing coffee powder, a compartment to be moved into sealed relationship against said delivery means, said compartment being in the form of a cylindrical jacket rigid with a movable hollow body which is sealedly mounted on a fixed hollow body to create a variable volume chamber connected to the operating pump of the dispenser.
The remaining objects are all attained according to the invention by a dispenser having the characteristics stated in the claims.